Magento 2 Custom Module Text Translation – Inline Translate Issues

Product data is not translated with CSV files per language, but stored per store view. Each store view has one language, so you should use the store specific values for translation.

Now this not only applies to product attributes but also to labels of custom options.

3. In the upper-left corner set Store View to the view for the translation. When prompted to confirm, tap OK.

4. For each field to be edited, do the following:

   a. Clear the Use Default Value checkbox to the right of the field.

   b. Either paste or type the translated text into the field.

   Make sure to translate all text fields, including image labels and Alt text, Search Engine Optimization fields and any Custom Options information.

5. When complete, tap Save.

^{Source: Magento 2.0 User Guide}

The $message is already translatable, because you use $this->__() to generate it. So, you can enable Inline Translation to translate it.

However, it is not best practise to use HTML code inside a translatable string. Imagine you string will some time be changed by your client - this will surely result in errors when HTML code needs to be changed. I would suggest the following solution:

<?php
    $headline = $this->__('Product added to cart');
    $text = $this->__('Go to the checkout to complete your purchase or add more products');
    $message = $this->__('<div class="notit"><span class="notification-symbol">%s</span><div class="rowt2"> <span class="added_cart">%s</span><br/><span class="small-text">%s</span></div></div>', $notifysymbol, $headline, $text);